It seems (to me anyway) that if you punish future crimes without making it known to them that you've punished them in particular, you prevent the crimes of anyone who one-boxes on newcomb, whereas if you let someone know you've punished them in particular, you only prevent the crimes of anyone who one-boxes on transparent newcomb. You should, therefore, make it known to the world that you will punish future crimes, and that you will do so in a way that will not become noticeable until after the crime has been committed.